1. Field of the Invention
The present invention relates to improvements to an intermittent motion type decorating machine for increasing the number of workpieces decorated per unit of time over that known in the art, and, more particularly, to improvements to a method and apparatus for decorating workpieces passed into and from one or more decorating stations at a greater rate per unit of time without impairing the intermittent decorating operation by a decorating screen as well as improvements to workpiece supply and delivery systems situated upstream and downstream of the workpiece flow through the decorating stations.
2. Description of the Prior Art
As shown in U.S. Pat. Nos. 2,231,535; 2,261,255; 2,721,516; and 3,146,705 intermittent motion type decorating machines are known in the art and provide a drive system to impart intermittent traveling motion to the workpieces such as containers made of glass or plastic. A container is moved through a predetermined distance, stopped, moved again through a predetermined distance, stopped and again moved until each container through the sequence of motions moves completely through the decorating stations of the machine. A decorating station will be provided at one or more places where the container comes to a stop. At the decorating station, a decorating screen is displaced into line contact with the surface of the container by an associated squeegee. During the decorating process, a synchronous speed relation is maintained at a line of contact established by the squeegee between the screen undergoing linear displacement and the container undergoing rotation.degree.. The squeegee remains stationary during the decorating process.degree.. Decorating machines of this type are particularly useful to decorate bottles and carryout the decoration process while the surface of the bottle to be decorated is horizontally orientated. In the aforesaid U.S. Pat. No. 2,261,255 there is disclosed moving a body screen and a shoulder screen at substantially the same peripheral linear speed as the body and shoulder portions of the bottle during the decorating operation. It was heretofore, as disclosed in the aforesaid patent number 3,251,298, believed that intermittent motions of decoration machines have limited production rates and can decorate 125 bottles per minute. It was believed in rare instances wherein exact timing is achieved, a production rate of 150 bottles per minute could be attained. The teaching in the art, at that time, was to decorate bottles at a bottle decorating rate of 150 bottles per minute by continuous decoration because of the limitation placed on intermittent type decorating machines.
In U.S. Pat. No. 3,388,574, there is shown a workpiece carrier device for supporting a bottle in a horizontal orientation while intermittently moved along a path of travel through a decorating apparatus. The bottle is supported at its opposite ends by clamping chucks one of which has a journal extending from a bearing support and the other of which can move to releasably contact a bottle for causing rotation about a horizontal axis. The bottle is rotated by a drive member brought into a driving relation with the protruding journal part of the bearing support. The clamping chucks are operatively supported on a base which is secured to chain-links forming an endless conveyor chain extending along the path of travel of bottles through the decorating apparatus.
Intermittent motion type bottle decorators are known in the art to provide, according to one construction of machine parts, a bottle decorating rate on the order of 100 to 125 bottles per minute. The decoration is carried out by establishing a decorating cycle essentially made up of two equal parts. One half of the decorating cycle is used for the decoration and the remaining half of the cycle is used for indexing movement of the bottle through the decorating machine. There was no overlap between the decorating and indexing cycles. During the first part of the decorating cycle, the screen is moved synchronous with the peripheral speed of the rotating bottle to avoid smearing during decoration at the line contact established by a squeegee with the bottle. When the screen moves to the end of its travel, the bottle has rotated 360.degree. whereupon the screen drive mechanism maintains the screen stationary for the remaining part of the decorating cycle while the bottle is moved from the decorating station and an undecorated bottle is positioned at the decorating station. The decorating cycle is then repeated. Robustly constructed drive mechanisms are necessary to withstand the forces of inertia and impact loading which occur due to the intermittent motion of the bottles to and from the decorating station, the rotation of the bottle for the decorating process and the drive mechanism for reciprocating the decorating screen back and forth at the decorating station.
The present invention provides an increase to the rate at which the bottles are decorated in an intermittent motion type decorating machine by improving not only the method and apparatus by which the bottles are decorated but also the equipment necessary to supply and deliver bottles from the decorating machine. As to the decoration of bottles it has been discovered that merely increasing the drive input speed of the machine will impose erratic behavior to the critical speed matching relation of the screen and bottle during decoration and wreck the machine parts because of force overloads. Moreover, the bottles must be handled with greater constraints as they are manipulated during the feeding operation from a source of supply and discharged from the decorating conveyor. The glass forming operations also impose dimensional variations to the bottles that must be accommodated during high speed handling by the bottle entry and delivery equipment as well as during the actual bottle decorating process.
The present invention seeks to provide a workpiece transferring apparatus to transfer workpieces individually from a supply conveyor to a decorating transfer conveyor and thence from a decorating transfer conveyor to a delivery conveyor in which the transfer operations are carried out simultaneously with an orientation of the workpiece. The change to the workpiece orientation, such when the workpiece comprises bottles, has been carried out in the past as shown in U.S. Pat. No. 3,648,821 in which a conveyor supplies the bottles in a vertical orientation to a point where they are transferred by a transfer device to a conveyor forming part of a decorating machine through an orientation from the vertical to the horizontal. The bottles are decorated while horizontally orientated and thence delivered from the decorating machine by a transfer device to a discharge conveyor. The transfer device orientates the bottles from the horizontal to the vertical for conveyance by the discharge conveyor. When the rate at which bottles are fed through the decorating machine increases, there also occurs the need to captively hold the bottle throughout each supply operation through the feed conveyor to the conveyor of the decorating machine and through the conveyor of the decorating machine to the delivery conveyor. Also, the motions necessary to grip and release the workpiece during these transferring operations must be executed with great precision to insure successful handling of the workpiece that necessarily requires that the workpiece be taken from the freestanding stable attitude, re-orientated and placed in a wholly confined driven conveyor and taken from the driven conveyor, re-orientated to again regain a free-standing stable attitude.